Waste chicken feathers could be used to create biodegradable thermoplastics for packaging as an alternative to petroleum based plastics.

Lead Researcher Yiqi Yang at the University of Nebraska-Lincoln, USA, explains, ‘We have tried to form many biobased materials, but feathers are better due to their improved mechanical properties and water stability and, of course, price.’

Poultry feathers contain the chemically stable and strengthening protein keratin, also found in hair, hooves and wool.

To form the plastic, the feathers are cleaned and treated with a one-step chemical modification process using methyl acrylate in a simple reactor at 50ºC. The methyl acrylate is grafted onto functional groups on the surface of the feathers for polymerisation.

The feather fibres are used as a principal ingredient rather than an additive, making up 50% of the material, notes Yang. This also means the feathers do not need to be combined with petroleum based plastics, such as polyethylene or polypropylene.

He adds, ‘[Instead] our work turns feathers into something like polyethylene and polypropylene. Therefore the plastics will be more degradeable and sustainable.’

So far, the team has produced feather-g-poly(methyl acrylate) with good thermoplasticity. ‘The feather films had substantially higher tensile properties than soy protein isolate and starch acetate films.’

Furthermore, Yang claims the keratin quantity means the thermoplastics perform well when wet, combating common problems associated with biobased materials that have poor resistance to hydrolysis.

In reference to the biomaterials’ durability, he adds ‘It could be reused, but not for as long as non-degradable thermoplastics. We do not want the bioplastics to be there forever, but to simply disappear after use. We hope to replace petroplastics with the feather bioplastics in many areas where they are in use, and as composite matrix materials or thermoplastic pellets for various applications. It could [also] be used as a packaging material and foam.’

However, Yang is reluctant to use the plastic in food packaging, as consumers may not be comfortable with the high feather content. The effects of graft polymerisation conditions, pH, temperature and time of polymerisation from monomer to polymer and grafting efficiency are being evaluated.

Malcom Harold of the Materials KTN, Polymers, says, ‘It must be borne in mind that this was a lab-scale feather to polymer success....The development time in labscale work is often forgotten. Scale-up can be very hard and/or expensive to complete.’

Harold adds, ‘The origin of the feathers will almost certainly guarantee it will never be used for food packaging, simply because many people object to meat and meat byproducts. This research has a long way to go for material and product optimisation but it is certainly one to watch.’